Time: 843 AM Tue August 17, 2021 Forecaster: Justin Brooks ------------------------- Heavy Precipitation Outlook Flash Flood Prediction Program ------------------------- HOT AND HAZY AGAIN WITH A VERY SLIGHT CHANCE FOR ISOALTED HIGH-BASED AFTERNOON/EARLY EVE RAIN SHOWERS/THUNDERSTORMS - Ridge of high-pressure continues to dominate over the region today keeping hazy conditions for Colorado. This high-pressure ridge will also keep high temperatures in the low to mid 90's this afternoon, 10 degrees above average for this time of year. - A weak disturbance will move through this afternoon resulting in a very slight chance for isolated high-based rain showers/thunderstorms. Biggest threat at this time will be gusty winds and a few lightning strikes as surface moisture mixes out through the morning bringing dew points into the mid to upper 30's, with a few low 40's possible in isolated areas. If dew points do not mix out entirely through the morning and into the afternoon a better chance for moderate to brief heavy rainfall will remain, although unlikely at this time. - Best chance for any storm development will be between 2-8pm with skies gradually clearing after sunset. Storm motions will be from the west to east today between 10-15mph which will also help limit point rainfall amounts this afternoon and early evening. Overnight will be mild as temperatures drop into the low to mid 60's on the plains with mid to upper 50's along the foothills. STORM RAINFALL POTENTIAL AND DURATION: Typical high-based rain showers/isolated thunderstorms will produce a trace to 0.10" in 10-30 minutes. A moderate rain showers/thunderstorm could produce 0.1-0.3" in 10-30 minutes. WORST CASE SCENARIO: A stationary moderate rain showers or brief strong thunderstorms has the potential to produce 0.3-0.8" in under 60 minutes. A LOOK AHEAD: High temperatures will remain elevated through tomorrow in the upper 80's to mid 90's across the plains with low to mid 80's along the foothills. Afternoon rain chances start to increase Wednesday with a slight chance we could see some isolated heavy rainfall, mainly along the foothills and Palmer Divide at this time. The best chance for heavy rainfall this week will be on Thursday as high temperatures cool into the upper 70's to low 80's behind a cold front with widespread rain showers/thunderstorms likely throughout the afternoon and evening. A chance for rain showers/thunderstorms continues on Friday as high temperatures stay in the upper 70's to low 80's. LOCATION PRIME TIME 30-Minute Rainfall and % Probability Message Potential Plains       Adams 200 PM TO 800 PM Trace (30%) to 0.1" (15%) to 0.3" (5%) NONE Arapahoe 200 PM TO 800 PM Trace (30%) to 0.1" (15%) to 0.3" (5%) NONE Boulder 200 PM TO 800 PM Trace (30%) to 0.1" (15%) to 0.3" (5%) NONE Broomfield 200 PM TO 800 PM Trace (30%) to 0.1" (15%) to 0.3" (5%) NONE Denver 200 PM TO 800 PM Trace (30%) to 0.1" (15%) to 0.3" (5%) NONE Douglas 200 PM TO 800 PM Trace (30%) to 0.1" (15%) to 0.3" (5%) NONE Jefferson 200 PM TO 800 PM Trace (30%) to 0.1" (15%) to 0.3" (5%) NONE Foothills above 6500ft       Boulder 200 PM TO 800 PM Trace (40%) to 0.1" (20%) to 0.3" (10%) NONE Douglas 200 PM TO 800 PM Trace (40%) to 0.1" (20%) to 0.3" (10%) NONE Jefferson 200 PM TO 800 PM Trace (40%) to 0.1" (20%) to 0.3" (10%) NONE MONITOR NATIONAL WEATHER SERVICE FOR SEVERE WEATHER STATEMENTS. MHFD Flood Prediction Center: 303-458-0789    F2P2 Website [http://udfcd.org/Flash+Flood+Prediction+Program]